1. Technical Field
The technology disclosed herein relates to an optical-axis adjustable lens barrel.
2. Background Information
The interchangeable lens digital cameras have been rapidly widespread in recent years. For example, some of such cameras are configured to convert an optical image of an object into an electric image signal and output the obtained electric image signal. Downsizing of the interchangeable lens barrels has been demanded for such digital cameras with the trend of downsizing of the camera bodies.
The lens barrel is embedded with a zoom lens configured to perform a zoom action. The zoom lens is movable along the optical axis within the lens barrel. The zoom lens is held by a lens holding frame. The zoom lens includes a guide shaft for guiding the lens holding frame in an optical axis direction. The guide shaft is supported by the lens barrel. Light from an object passes through a lens system including the zoom lens, and an optical image of the object is imaged in an image sensor.
In such lens systems, the optical axis of the zoom lens may be tilted with respect to the optical axis of a fixed lens fixed to the lens barrel due to a variety of factors such as size errors of the lens holding frame and the lens barrel or variation in accuracy of attaching the lens to the lens holding frame. The tilted optical axis may cause focus blur (e.g., partial blur) in the optical image of the object to be imaged on the imaging surface of the image sensor.
In view of the above, Japan Laid-open Patent Application Publication No. JP-A-2006-227170 describes a construction of a lens barrel configured to adjust the tilt of the optical axis of the zoom lens. Specifically, the publication discloses a bearing member. The bearing member includes a shaft portion and a bearing hole. The shaft portion of the bearing member is detachably inserted into a hole of the lens barrel from the outside. The bearing hole has a center axis displaced from that of the shaft portion. In the publication, multiple bearing members are prepared and the inter-axes displacements thereof are different from each other. In assembling the lens barrel, the optimal one of the bearing members is selected and attached to the lens barrel in accordance with the tilt of the optical axis, and the optical axis is thereby adjusted.
In downsizing a lens barrel including an adjusting mechanism, it is required not only to simply downsize an image optical system but also to efficiently dispose the adjusting mechanism and the other components in a limited space without spatial interference among the components. It is also required to form the adjusting mechanism and the other components in optimal shapes for disposing them in a limited space.